Thread: Apologies for the VERY basic newbie question...

I'm trying to write some code that will allow me to enter text of an arbitrary length. I think I need to use an array for this. Here's my code...

Code:

#include <stdio.h>

main()
               
        {
        char InputText[100];         /* Character Array setup  */        
        printf("Hello, enter some text...\n this program uses \"inputText[100] to hold the text\" \n\n\t");
        scanf("%s", &InputText);
        }

It works, but not as I expected. I thought the number in square brackets dictated the number of characters that could be entered. However, the resultant program just seems to allow me to enter as much text as I like, no matter what number I place within the brackets!

Would some kind soul please explain (preferably in simple terms)

C does not have an array bound checking so even if you create an array of size 1, it will show no error in accepting hundreds of characters/data. But you might not be able to access them since they're not allocated.

Originally Posted by Iiz

C does not have an array bound checking so even if you create an array of size 1, it will show no error in accepting hundreds of characters/data. But you might not be able to access them since they're not allocated.

From what liz is saying, there seems no point in the numerical values! (In other words, I don't understand)

However, the resultant program just seems to allow me to enter as much text as I like, no matter what number I place within the brackets!

Yes the program you supplied will allow you to enter any number of characters into your string. However you are not using the scan() properly to avoid this serious problem. You should never use a function that retrieves a string that doesn't limit the number of characters it will try to retrieve. To limit the number of characters scanf() will try to retrieve into a string you need to use the proper width specifier. Something more like:

Code:

char buffer[10];
printf("Please enter a string: ");
scanf("%9s", buffer); // See the note below.
printf("%s", buffer);

Note: Notice the difference between the size of the array (10) and the width specifer (9), you must reserve room for the end of string character that is automatically added to the string by scanf().

By the way you need to also remember that scanf() will also stop processing the string when it encounters a white space character, if you want to retrieve a string that has white space you should use fgets() instead.

Jim